More than a decade ago the Ascom Timeplex Company developed and introduced to a world-wide market high speed data transmission equipment under the tradename LINK/2.TM.. This equipment enabled a user, such as a bank, insurance company, etc., having offices at different locations (e.g., New York and London) to transmit virtually instantly and in a highly cost effective way volumes of data between locations. The LINK/2.TM. equipment has proven to be very efficient and highly cost effective. As a result it has achieved great customer acceptance and captured a large share of the market all over the world. It is estimated that the value of the existing installed base of LINK/2.TM. equipment is now over a billion dollars.
At the time the LINK/2.TM. was being developed it was decided to utilize a 9-bit byte in its operating protocol. An extra, or 9th binary bit, was added to 8 "data" bits in each byte in order to signify whether the byte represented a "function" or user data.
In recent years there have been important advances in technology relating to data transmission, particularly with regard to new semiconductor devices, increased speed of the devices and of communication links, much higher density of integrated circuits, better costs, and so forth. Ascom Timeplex, in order to take advantage of this new technology developed and recently introduced to the market a new class of equipment under the tradename "Synchrony.TM.". Because of factors which did not exist earlier when LINK/2.TM. was developed, the new Synchrony.TM. equipment is designed to operate with an 8 bit per byte protocol.
A customer who buys the new Synchrony.TM. equipment may already be using LINK/2.TM. equipment. It is therefore highly desirable for maximum utility of both systems that they be able to transmit data back and forth to each other in unimpeded fashion. But because the Synchrony.TM. equipment operates with bytes of 8 bits in length versus 9-bit bytes for the LINK/2.TM. equipment, effective, high speed communication between the new and the old equipment has posed a difficult problem.
In order to provide for unimpeded communications between LINK/2.TM. and Synchrony equipments, a module termed a "link gateway module" (LGM) can be added to the Synchrony.TM. equipment. The LGM in its various operations) not otherwise discussed herein) processes data in the form of 9-bit bytes as employed by LINK/2.TM. and data in the form of 8-bit bytes as employed by Synchrony.TM.. A critical need of the LGM therefore is the ability to convert bytes having a given number of bits into bytes having a different number of bits. At various stages in its operation the LGM needs to convert from 9-bit bytes to 8-bit bytes, to convert from 8-bit bytes to 9-bit bytes, and also to convert from 9-bit bytes to 7-bit bytes, to convert from 7-bit bytes to 9-bit bytes and to convert from 7-bit bytes to 8-bit bytes. Of course the various conversions must be done with absolute accuracy virtually instantaneously without queuing of data, and in a cost-effective way.
The present invention provides a simple, cost effective, and highly efficient solution to the problem of converting data existing in the form of bytes of a given bit length to equivalent data in the form of bytes having a different bit length (either greater or smaller).